A disinfection high-efficiency air filter paper and its preparation method

Abstract

This invention discloses a high-efficiency disinfection air filter paper and its preparation method, relating to the field of filter material technology. The invention first utilizes ethylene (chloromethyl)dimethoxysilane to modify nano-titanium dioxide, N-(2,3-epoxypropyl)phthalamide, and chitosan to generate an antibacterial agent. This agent is then copolymerized with N-hydroxymethylacrylamide and acrylamide to form an antibacterial emulsion. A multi-layer polyvinylidene fluoride nanofiber composite membrane is then prepared by combining a scaffolded polyvinylidene fluoride fiber membrane with an ultra-fine polyvinylidene fluoride fiber membrane, achieving a low-resistivity filter paper. Finally, the antibacterial emulsion is sprayed onto the surface, promoting the fixation of the modified titanium dioxide onto the substrate surface and improving the filter paper's burst resistance. The filter paper prepared by this invention exhibits antibacterial, burst-resistant, and low-resistivity properties.

Description

Technical Field

[0001] This invention relates to the field of filter paper technology, specifically to a high-efficiency disinfection air filter paper and its preparation method. Background Technology

[0002] Air is one of the essential conditions for human survival, covering every corner of the earth. The types and quantities of particulate matter in the air have changed. These particles include soil dust, coal combustion, vehicle exhaust, and PM, among which PM2.5 particles are small in size, highly buoyant, and have a large surface area. They can adsorb a large amount of toxic, harmful, and heavy metal pollutants, which can accumulate in the lungs and even the circulatory system, causing respiratory diseases or thrombosis. They can also adsorb a large amount of toxic substances such as organic gases, viruses, and bacteria, and remain in the atmosphere for a long time, affecting human health and air quality. With social development and the popularization of health knowledge, people have paid attention to the harm of fine particulate pollution in the air and have increasingly valued their living air environment and living experience. As a result, air filters have become an essential household appliance, and air filter paper is the core component of the filtration function. In order to achieve the purpose of air purification, it is necessary to invent a highly efficient disinfection air filter paper to reduce the entry of harmful particles into the lungs or effectively intercept harmful gases emitted from the environment. Summary of the Invention

[0003] The purpose of this invention is to provide a highly efficient disinfection air filter paper and its preparation method, so as to solve the problems existing in the prior art.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a disinfection high-efficiency air filter paper, wherein the disinfection high-efficiency air filter paper is prepared by spraying an antibacterial emulsion onto a polyvinylidene fluoride nanofiber composite membrane.

[0005] Furthermore, the antibacterial emulsion is prepared by copolymerizing an antibacterial agent made of N-(2,3-epoxypropyl)phthalamide, chitosan, and modified titanium dioxide with N-hydroxymethylacrylamide and acrylamide.

[0006] Furthermore, the modified nano-titanium dioxide is prepared by modifying nano-titanium dioxide with ethylene (chloromethyl)dimethoxysilane.

[0007] Furthermore, the polyvinylidene fluoride nanofiber composite membrane is made by combining a scaffolded polyvinylidene fluoride fiber membrane with an ultrafine polyvinylidene fluoride fiber membrane.

[0008] Furthermore, a method for preparing a high-efficiency disinfecting air filter paper includes the following preparation steps:

[0009] (1) Mix nano-titanium dioxide and 15wt% dilute hydrochloric acid solution at a mass ratio of 1:60 to 1.3:65, sonicate at 25kHz for 30 min, stir at 70 to 100 rpm for 3 to 5 h, add distilled water until the solution pH is 7, then add anhydrous ethanol at 85 to 100 times the mass of nano-titanium dioxide, filter, take the solid, wash with ethanol 3 times, vacuum dry at 50℃ for 2 to 3 h, add 10 to 15 times the mass of nano-titanium dioxide in an 80% ethanol aqueous solution, while stirring at 50 to 70 rpm and adding 0.7 to 1 times the mass of nano-titanium dioxide in ethylene (chloromethyl)dimethoxysilane, sonicate at 40℃ and 25kHz for 40 min, then raise the temperature to 70 to 100℃ and react for 22 to 26 h, cool to room temperature, filter, take the solid, wash with distilled water 3 times, vacuum dry at 50℃ for 2 to 3 h to obtain modified titanium dioxide;

[0010] (2) Mix chitosan and distilled water at a mass ratio of 6:8 to 7:10, heat to 80°C, stir at 70 to 100 rpm for 30 min, add N-(2,3-epoxypropyl)phthalamide at 2 to 4 times the mass of chitosan in three portions over 2 h, react for 10 h, pour in acetone at 30 to 35 times the mass of chitosan, stir at 70 to 100 rpm for 1 h, react at 0 to 4°C for 12 to 15 h, pour off the supernatant, dissolve the remaining gel-like product in methanol at 15 to 18 times the mass of chitosan, add acetone mixture at 25 to 29 times the mass of chitosan, the mass ratio of acetone to ethanol in the acetone mixture is 4:1, let stand for 2 to 3 h, filter, take the solid, wash twice with ethanol at 50 to 65°C, dry at 70°C for 4 to 6 h to obtain modified chitosan;

[0011] (3) Mix modified titanium dioxide, dichloromethane and modified chitosan in a mass ratio of 1:20:0.7 to 1:20:0.9 and react in a water bath at 35°C for 4 to 6 hours. Then heat to 60°C and distill under a vacuum of 1.4 to 3 kPa for 2 to 3 hours. Let stand for 5 to 8 hours to obtain intermediate A.

[0012] (4) Acrylamide, N-hydroxymethylacrylamide, and intermediate A are mixed evenly in a mass ratio of 5:1.8:3.5 to 7:2.2:5. Then, 0.7 g / s is added to a composite emulsifier with a mass ratio of 1.7 to 2.3 times that of acrylamide, and 3 to 4 times that of acrylamide is added to deionized water. The mixture is stirred at 100 to 200 rpm for 30 min to obtain a pre-emulsion. Deionized water, composite emulsifier, and sodium bicarbonate buffer solution are mixed in a mass ratio of 7:2:0.1 to 10:4:0.2. The mixture is heated to 75°C in a water bath. 1 / 3 of the pre-emulsion and 1 / 2 of the ammonium persulfate initiator are added. The mixture is heated to 85°C. The remaining pre-emulsion and initiator are added at 3.5 h and 4 h of reaction, respectively. The mixture is heated for another 2 h. The supernatant is poured off to obtain an antibacterial emulsion.

[0013] (5) Polyvinylidene fluoride (M W =300,000), fluorinated polyurethane and dimethylformamide are mixed and stirred at 60℃ and 400rpm until the solution is transparent to obtain a scaffold polyvinylidene fluoride / fluorinated polyurethane spinning solution. Tetrabutylammonium chloride is then added, and electrospinning is performed. The spinning process parameters are: spinning flow rate 10mm / min, positive voltage 25kV, negative voltage 2kV, and receiving distance 18cm to obtain a scaffold polyvinylidene fluoride fiber membrane.

[0014] (6) Mix polyvinylidene fluoride (Mw = 600,000) and dimethylformamide at a mass ratio of 0.2:8 to 0.5:10, and stir at 40°C and 500 rpm until the solution is transparent to obtain an ultrafine polyvinylidene fluoride spinning solution. Then, perform electrospinning with the following spinning process parameters: spinning flow rate 5 mm / min, positive voltage 30 kV, negative voltage 2 kV, and receiving distance 22 cm to obtain an ultrafine polyvinylidene fluoride fiber membrane. Stack the membrane layer by layer with the scaffold polyvinylidene fluoride fiber membrane to four layers and sew them together to obtain a polyvinylidene fluoride nanofiber composite membrane.

[0015] (7) Spray the antibacterial emulsion evenly on both sides of the polyvinylidene fluoride nanofiber composite membrane with a thickness of 0.3 mm. After standing at room temperature for 30 to 60 minutes, spray a second time with a thickness of 0.5 mm. Dry at 100 to 120°C for 2 hours to obtain disinfected high-efficiency air filter paper.

[0016] Furthermore, the vacuum degree mentioned in step (1) is 0.2 to 1 kPa.

[0017] Further, the preparation method of the composite emulsifier in step (4) is as follows: sodium dodecylbenzenesulfonate, alkylphenol polyoxyethylene ether, and distilled water are mixed in a mass ratio of 4:1:13 to 6:1:17, and acrylamide of 1.4 to 1.9 times the mass of sodium dodecylbenzenesulfonate is added dropwise to the solution at 0.3 to 0.5 mL / s. The mixture is stirred at 70 to 100 rpm for 30 min to obtain the composite emulsifier.

[0018] Furthermore, the mass ratio of ammonium persulfate initiator to acrylamide in step (4) is 0.7:1 to 0.9:1.

[0019] Furthermore, the polyvinylidene fluoride (M) described in step (5) W =300,000), fluorinated polyurethane, dimethylformamide, and tetrabutylammonium chloride are in a mass ratio of 1:5:0.8:0.9 to 3:10:1.3:2.5.

[0020] Furthermore, the spinning environment described in steps (5) and (6) is a temperature of 25°C and a humidity of 30%.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0022] This invention involves spraying an antibacterial emulsion onto a polyvinylidene fluoride nanofiber composite membrane and then using electrospinning technology to produce filter paper, thereby achieving antibacterial, tear-resistant, and low-resistance effects.

[0023] First, the antibacterial emulsion is a copolymer of an antibacterial agent made from N-(2,3-epoxypropyl)phthalamide, chitosan, N-hydroxymethylacrylamide, and modified nano-titanium dioxide, and acrylamide. Specifically, the epoxy groups of N-(2,3-epoxypropyl)phthalamide react with chitosan to form primary amine groups. Then, under the action of ethylene(chloromethyl)dimethoxysilane-modified titanium dioxide, the amino groups of N-(2,3-epoxypropyl)phthalamide are converted into permanently positively charged quaternary ammonium groups, achieving basic antibacterial properties. Simultaneously, chitosan and titanium dioxide work together to assist the quaternary ammonium structure, jointly enhancing antibacterial activity. Next, the primary amine groups complex with the hydroxyl groups in N-hydroxymethylacrylamide via hydrogen bonds and participate in the copolymerization of acrylamide and N-hydroxymethylacrylamide with modified titanium dioxide, forming a multi-molecular cross-linked structure that enhances antibacterial properties. At the same time, the modified titanium dioxide is uniformly dispersed and fixed on the matrix surface, forming a rough surface structure rich in porous particles, thus exhibiting tear resistance.

[0024] Secondly, the polyvinylidene fluoride (PVDF) nanofiber composite membrane is made by combining a scaffolded PVDF / fluorinated polyurethane fiber membrane with an ultra-fine PVDF fiber membrane. During the spinning process, tetrabutylammonium chloride is added to increase the charge density of the PVDF-fluorinated polyurethane polymer, allowing the long-chain organic molecular structures of the two to interpenetrate the fibers and form a tight connection between the fiber membranes, achieving a burst-resistant composite membrane. It also gives the spun fiber membranes small pore size and uniform structure, resulting in a fluffy composite membrane with high porosity and low resistance. At the same time, the presence of fluorinated polyurethane enables acrylamide to form hydrogen bonds with the fiber membrane, enhancing the interaction between the emulsion and the PVDF nanofiber composite membrane. This strengthens the filter paper's burst resistance even after repeated friction, ensuring the matrix retains strong antibacterial properties and molecular forces. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] To more clearly illustrate the method provided by the present invention, the following embodiments are provided in detail. The testing methods for various indicators of the disinfection high-efficiency air filter paper prepared in the following embodiments are as follows:

[0027] Antibacterial properties: The antibacterial effect was tested on the same size of the example and the comparative example, and the antibacterial rate was measured according to GB / T20944.3.

[0028] Bursting strength: The tensile strength and elongation of the film were tested using an XLW(EC)-a type film tensile strength tester. The test length was 5 cm and the width was 2 cm. The tensile rate was 20 mm / min, the pre-tension was 0.2 cN, and the average value was taken after 5 tests.

[0029] Low resistance: Examples and comparative examples of the same size were used, and the filtration performance of the membrane material was tested using sodium chloride aerosol with a TSI-8130 automatic filter media testing system to test its retention rate and air resistance.

[0030] Example 1

[0031] (1) Mix nano-titanium dioxide and 15wt% dilute hydrochloric acid solution at a mass ratio of 1:60, sonicate at 25kHz for 30 min, stir at 70rpm for 3 h, add distilled water until the solution pH is 7, then add anhydrous ethanol at 85 times the mass of nano-titanium dioxide, filter, take the solid, wash with ethanol 3 times, dry at 50℃ and vacuum degree of 0.2kPa for 2 h, add 80% ethanol aqueous solution at 10 times the mass of nano-titanium dioxide, and at the same time add ethylene (chloromethyl)dimethoxysilane at 0.7 times the mass of nano-titanium dioxide while stirring at 50rpm, sonicate at 25kHz for 40 min at 40℃, then raise the temperature to 70℃, react for 22 h, cool to room temperature, filter, take the solid, wash with distilled water 3 times, dry at 50℃ and vacuum degree of 0.2kPa for 2 h to obtain modified titanium dioxide;

[0032] (2) Chitosan and distilled water were mixed at a mass ratio of 6:8, heated to 80°C, and stirred at 70 rpm for 30 min. N-(2,3-epoxypropyl)phthalamide, which was twice the mass of chitosan, was added in three portions over 2 h. After reacting for 10 h, acetone, which was 30 times the mass of chitosan, was added and stirred at 70 rpm for 1 h. After reacting at 0°C for 12 h, the supernatant was poured off. The remaining gel-like product was dissolved in methanol, which was 15 times the mass of chitosan. A mixture of acetone and ethanol, which was 25 times the mass of chitosan, was added. The mass ratio of acetone to ethanol in the acetone mixture was 4:1. After standing for 2 h, the mixture was filtered, and the solid was washed twice with ethanol at 50°C and dried at 70°C for 4 h to obtain modified chitosan.

[0033] (3) Modified titanium dioxide, dichloromethane and modified chitosan were mixed in a mass ratio of 1:20:0.7 and reacted in a water bath at 35°C for 4 hours. Then the temperature was raised to 60°C and distilled under a vacuum of 1.4 kPa for 2 hours. After standing for 5 hours, intermediate A was obtained.

[0034] (4) Sodium dodecylbenzenesulfonate, alkylphenol polyoxyethylene ether, and distilled water were mixed in a mass ratio of 4:1:13. Acrylamide, at a mass ratio of 1.4 times that of sodium dodecylbenzenesulfonate, was added dropwise to the solution at 0.3 mL / s. The mixture was stirred at 70 rpm for 30 min to obtain a composite emulsifier. Acrylamide, N-hydroxymethylacrylamide, and intermediate A were mixed evenly in a mass ratio of 5:1.8:3.5. This mixture was then added at a mass ratio of 0.7 g / s to the composite emulsifier, at a mass ratio of 1.7 times that of acrylamide, and 3 times that of acrylamide was added. Deionized water was stirred at 100 rpm for 30 min to obtain a pre-emulsion. Deionized water, composite emulsifier, and sodium bicarbonate buffer solution were mixed at a mass ratio of 7:2:0.1 and heated in a water bath to 75°C. One-third of the pre-emulsion and half of the ammonium persulfate initiator were added, and the mixture was heated to 85°C. The remaining pre-emulsion and initiator were added at 3.5 h and 4 h of reaction, respectively, and the mixture was heated for another 2 h. The supernatant was then poured off to obtain an antibacterial emulsion. The mass ratio of the ammonium persulfate initiator to acrylamide was 0.7:1.

[0035] (5) Polyvinylidene fluoride (MW = 300,000), fluorinated polyurethane and dimethylformamide are mixed and stirred at 60°C and 400 rpm until the solution is transparent to obtain a scaffolded polyvinylidene fluoride / fluorinated polyurethane spinning solution. Tetrabutylammonium chloride is then added, and electrospinning is performed at an ambient temperature of 25°C and a humidity of 30%. The spinning process parameters are: spinning flow rate 10 mm / min, positive voltage 25 kV, negative voltage 2 kV, and receiving distance 18 cm to obtain a scaffolded polyvinylidene fluoride fiber membrane. The mass ratio of polyvinylidene fluoride (MW = 300,000), fluorinated polyurethane, dimethylformamide and tetrabutylammonium chloride is 1:5:0.8:0.9.

[0036] (6) Polyvinylidene fluoride (Mw = 600,000) and dimethylformamide are mixed at a mass ratio of 0.2:8 and stirred at 40°C and 500 rpm until the solution is transparent to obtain an ultrafine polyvinylidene fluoride spinning solution. Then, electrospinning is carried out at an ambient temperature of 25°C and a humidity of 30%. The spinning process parameters are: spinning flow rate 5 mm / min, positive voltage 30 kV, negative voltage 2 kV, and receiving distance 22 cm to obtain an ultrafine polyvinylidene fluoride fiber membrane. The membrane is then stacked layer by layer with the scaffolded polyvinylidene fluoride fiber membrane to four layers and sewn together to obtain a polyvinylidene fluoride nanofiber composite membrane.

[0037] (7) Spray the antibacterial emulsion evenly on both sides of the polyvinylidene fluoride nanofiber composite membrane with a thickness of 0.3 mm. After standing at room temperature for 30 min, spray a second time with a thickness of 0.5 mm. Dry at 100℃ for 2 h to obtain disinfected high-efficiency air filter paper.

[0038] Example 2

[0039] (1) Nano-titanium dioxide and 15wt% dilute hydrochloric acid solution were mixed at a mass ratio of 1.2:63. After sonication at 25kHz for 30min, the mixture was stirred at 85rpm for 4h. Distilled water was added until the pH of the solution was 7. Then, anhydrous ethanol with a mass ratio of 93 times that of nano-titanium dioxide was added. The mixture was filtered, and the solid was taken. After washing with ethanol three times, the solid was dried at 50℃ and vacuum degree of 0.6kPa for 2.5h. An 80% ethanol aqueous solution with a mass ratio of 12 times that of nano-titanium dioxide was added. At the same time, ethylene (chloromethyl)dimethoxysilane with a mass ratio of 0.85 times that of nano-titanium dioxide was added while stirring at 65rpm. The mixture was sonicated at 40℃ and 25kHz for 40min. The temperature was then raised to 85℃ and reacted for 24h. After cooling to room temperature, the solid was filtered, and the solid was taken. After washing with distilled water three times, the solid was dried at 50℃ and vacuum degree of 0.6kPa for 2.5h to obtain modified titanium dioxide.

[0040] (2) Chitosan and distilled water were mixed at a mass ratio of 6.5:9 and heated to 80°C. The mixture was stirred at 85 rpm for 30 min. N-(2,3-epoxypropyl)phthalamide, which was 3 times the mass of chitosan, was added in three portions over 2 h. After reacting for 10 h, acetone, which was 33 times the mass of chitosan, was added and stirred at 85 rpm for 1 h. After reacting at 2°C for 13.5 h, the supernatant was poured off. The remaining gel-like product was dissolved in methanol, which was 16.5 times the mass of chitosan. A mixture of acetone and ethanol, which was 27 times the mass of chitosan, was added. The mass ratio of acetone to ethanol in the acetone mixture was 4:1. After standing for 2.5 h, the mixture was filtered, and the solid was washed twice with ethanol at 58°C and dried at 70°C for 5 h to obtain modified chitosan.

[0041] (3) Modified titanium dioxide, dichloromethane and modified chitosan were mixed in a mass ratio of 1:20:0.8 and reacted in a water bath at 35°C for 5 hours. Then the temperature was raised to 60°C and the mixture was distilled under a vacuum of 2.1 kPa for 2.5 hours. After standing for 6.5 hours, intermediate A was obtained.

[0042] (4) Sodium dodecylbenzenesulfonate, alkylphenol polyoxyethylene ether, and distilled water are mixed in a mass ratio of 5:1:15. Acrylamide, at a mass ratio of 1.6 times that of sodium dodecylbenzenesulfonate, is added dropwise to the solution at 0.4 mL / s. The mixture is stirred at 80 rpm for 30 min to obtain a composite emulsifier. Acrylamide, N-hydroxymethylacrylamide, and intermediate A are mixed evenly in a mass ratio of 6:2:4. The mixture is then added at a mass ratio of 0.7 g / s to a composite emulsifier at a mass ratio of 2 times that of acrylamide, and deionized water, at a mass ratio of 3.5 times that of acrylamide, is also added. The mixture was stirred at 150 rpm for 30 min to obtain a pre-emulsion. Deionized water, composite emulsifier, and sodium bicarbonate buffer solution were mixed in a mass ratio of 8.5:3:0.15 and heated in a water bath to 75°C. One-third of the pre-emulsion and half of the ammonium persulfate initiator were added, and the mixture was heated to 85°C. The remaining pre-emulsion and initiator were added at 3.5 h and 4 h of reaction, respectively, and the mixture was heated for another 2 h. The supernatant was then poured off to obtain an antibacterial emulsion. The mass ratio of the ammonium persulfate initiator to acrylamide was 0.8:1.

[0043] (5) Polyvinylidene fluoride (MW = 300,000), fluorinated polyurethane and dimethylformamide are mixed and stirred at 60°C and 400 rpm until the solution is transparent to obtain a scaffold polyvinylidene fluoride / fluorinated polyurethane spinning solution. Tetrabutylammonium chloride is then added, and electrospinning is performed at an ambient temperature of 25°C and a humidity of 30%. The spinning process parameters are: spinning flow rate 10 mm / min, positive voltage 25 kV, negative voltage 2 kV, and receiving distance 18 cm to obtain a scaffold polyvinylidene fluoride fiber membrane. The mass ratio of polyvinylidene fluoride (MW = 300,000), fluorinated polyurethane, dimethylformamide and tetrabutylammonium chloride is 2:7.5:1.1:1.7.

[0044] (6) Polyvinylidene fluoride (Mw = 600,000) and dimethylformamide are mixed at a mass ratio of 0.35:9 and stirred at 40°C and 500 rpm until the solution is transparent to obtain an ultrafine polyvinylidene fluoride spinning solution. Then, electrospinning is carried out at an ambient temperature of 25°C and a humidity of 30%. The spinning process parameters are: spinning flow rate 5 mm / min, positive voltage 30 kV, negative voltage 2 kV, and receiving distance 22 cm to obtain an ultrafine polyvinylidene fluoride fiber membrane. The membrane is then stacked layer by layer with the scaffolded polyvinylidene fluoride fiber membrane to four layers and sewn together to obtain a polyvinylidene fluoride nanofiber composite membrane.

[0045] (7) Spray the antibacterial emulsion evenly on both sides of the polyvinylidene fluoride nanofiber composite membrane with a thickness of 0.3 mm. After standing at room temperature for 45 min, spray a second time with a thickness of 0.5 mm. Dry at 115℃ for 2 h to obtain disinfected high-efficiency air filter paper.

[0046] Example 3

[0047] (1) Nano titanium dioxide and 15wt% dilute hydrochloric acid solution were mixed at a mass ratio of 1.3:65. After sonication at 25kHz for 30min, the mixture was stirred at 100rpm for 5h. Distilled water was added until the pH of the solution was 7. Then, anhydrous ethanol with a mass ratio of 100 times that of nano titanium dioxide was added. The mixture was filtered, and the solid was taken. After washing with ethanol three times, the solid was dried at 50℃ and vacuum degree of 1kPa for 3h. An 80% ethanol aqueous solution with a mass ratio of 15 times that of nano titanium dioxide was added. At the same time, ethylene (chloromethyl)dimethoxysilane with a mass ratio of 1 times that of nano titanium dioxide was added while stirring at 70rpm. The mixture was sonicated at 40℃ and 25kHz for 40min. The temperature was then raised to 100℃ and reacted for 26h. After cooling to room temperature, the solid was filtered, and the solid was taken. After washing with distilled water three times, the solid was dried at 50℃ and vacuum degree of 1kPa for 3h to obtain modified titanium dioxide.

[0048] (2) Chitosan and distilled water were mixed at a mass ratio of 7:10, heated to 80°C, and stirred at 100 rpm for 30 min. N-(2,3-epoxypropyl)phthalamide, which was 4 times the mass of chitosan, was added in three portions over 2 h. After reacting for 10 h, acetone, which was 35 times the mass of chitosan, was added and stirred at 100 rpm for 1 h. After reacting at 4°C for 15 h, the supernatant was poured off. The remaining gel-like product was dissolved in methanol, which was 18 times the mass of chitosan. A mixture of acetone and ethanol, which was 29 times the mass of chitosan, was added. The mass ratio of acetone to ethanol in the acetone mixture was 4:1. After standing for 3 h, the mixture was filtered, and the solid was washed twice with ethanol at 65°C and dried at 70°C for 6 h to obtain modified chitosan.

[0049] (3) The modified titanium dioxide, dichloromethane and modified chitosan were mixed in a mass ratio of 1:20:0.9 and reacted in a water bath at 35°C for 6 hours. Then the temperature was raised to 60°C and distilled under a vacuum of 3 kPa for 3 hours. After standing for 8 hours, intermediate A was obtained.

[0050] (4) Sodium dodecylbenzenesulfonate, alkylphenol polyoxyethylene ether, and distilled water were mixed in a mass ratio of 6:1:17. Acrylamide, at a mass ratio of 1.9 times that of sodium dodecylbenzenesulfonate, was added dropwise to the solution at 0.5 mL / s. The mixture was stirred at 100 rpm for 30 min to obtain a composite emulsifier. Acrylamide, N-hydroxymethylacrylamide, and intermediate A were mixed evenly in a mass ratio of 7:2.2:5. The mixture was then added to the composite emulsifier at a mass ratio of 0.7 g / s, at a mass ratio of 2.3 times that of acrylamide, and 4 times that of acrylamide was added. Ionized water was stirred at 200 rpm for 30 min to obtain a pre-emulsion. Deionized water, composite emulsifier, and sodium bicarbonate buffer solution were mixed at a mass ratio of 10:4:0.2 and heated to 75°C in a water bath. One-third of the pre-emulsion and half of the ammonium persulfate initiator were added, and the mixture was heated to 85°C. The remaining pre-emulsion and initiator were added at 3.5 h and 4 h of reaction, respectively, and the mixture was heated for another 2 h. The supernatant was then poured off to obtain an antibacterial emulsion. The mass ratio of the ammonium persulfate initiator to acrylamide was 0.9:1.

[0051] (5) Polyvinylidene fluoride (MW = 300,000), fluorinated polyurethane and dimethylformamide are mixed and stirred at 60°C and 400 rpm until the solution is transparent to obtain a scaffolded polyvinylidene fluoride / fluorinated polyurethane spinning solution. Tetrabutylammonium chloride is then added, and electrospinning is performed at an ambient temperature of 25°C and a humidity of 30%. The spinning process parameters are: spinning flow rate 10 mm / min, positive voltage 25 kV, negative voltage 2 kV, and receiving distance 18 cm to obtain a scaffolded polyvinylidene fluoride fiber membrane. The mass ratio of polyvinylidene fluoride (MW = 300,000), fluorinated polyurethane, dimethylformamide and tetrabutylammonium chloride is 3:10:1.3:2.5.

[0052] (6) Polyvinylidene fluoride (Mw = 600,000) and dimethylformamide are mixed at a mass ratio of 0.5:10 and stirred at 40°C and 500 rpm until the solution is transparent to obtain an ultrafine polyvinylidene fluoride spinning solution. Then, electrospinning is carried out at an ambient temperature of 25°C and a humidity of 30%. The spinning process parameters are: spinning flow rate 5 mm / min, positive voltage 30 kV, negative voltage 2 kV, and receiving distance 22 cm to obtain an ultrafine polyvinylidene fluoride fiber membrane. The membrane is then stacked layer by layer with the scaffolded polyvinylidene fluoride fiber membrane to four layers and sewn together to obtain a polyvinylidene fluoride nanofiber composite membrane.

[0053] (7) Spray the antibacterial emulsion evenly on both sides of the polyvinylidene fluoride nanofiber composite membrane with a thickness of 0.3 mm. After standing at room temperature for 60 min, spray a second time with a thickness of 0.5 mm. Dry at 120℃ for 2 h to obtain disinfected high-efficiency air filter paper.

[0054] Comparative Example 1

[0055] The difference between Comparative Example 1 and Example 2 is that steps (1) and (2) are omitted, and step (3) is changed to: titanium dioxide, dichloromethane and chitosan are mixed in a mass ratio of 1:20:0.8 and reacted in a water bath at 35°C for 5 hours, then heated to 60°C, distilled under a vacuum of 2.1 kPa for 2.5 hours, and allowed to stand for 6.5 hours to obtain intermediate A; the remaining steps are the same as in Example 2.

[0056] Comparative Example 2

[0057] The difference between Comparative Example 2 and Example 2 is that step (6) is omitted, and step (5) is changed to: mixing polyvinylidene fluoride (MW = 300,000), fluorinated polyurethane and dimethylformamide, stirring at 60°C and 400 rpm until the solution is transparent to obtain a scaffold polyvinylidene fluoride / fluorinated polyurethane spinning solution, then adding tetrabutylammonium chloride, and then electrospinning at an ambient temperature of 25°C and a humidity of 30%. The spinning process parameters are: spinning flow rate 10 mm / min, positive voltage 25 kV, negative voltage 2 kV, and receiving distance 18 cm to obtain a scaffold polyvinylidene fluoride fiber membrane, which is stacked to four layers and sewn together to obtain a polyvinylidene fluoride nanofiber composite membrane; the mass ratio of polyvinylidene fluoride (MW = 300,000), fluorinated polyurethane, dimethylformamide and tetrabutylammonium chloride is 2:7.5:1.1:1.7; the remaining steps are the same as in Example 2.

[0058] Comparative Example 3

[0059] The difference between Comparative Example 3 and Example 3 is that step (5) is omitted, and step (6) is changed to: polyvinylidene fluoride (Mw = 600,000) and dimethylformamide are mixed at a mass ratio of 0.35:9 and stirred at 40°C and 500 rpm until the solution is transparent to obtain an ultrafine polyvinylidene fluoride spinning solution. Then, electrospinning is performed at an ambient temperature of 25°C and a humidity of 30%. The spinning process parameters are: spinning flow rate 5 mm / min, positive voltage 30 kV, negative voltage 2 kV, and receiving distance 22 cm to obtain an ultrafine polyvinylidene fluoride fiber membrane. The membrane is stacked into four layers and sewn together to obtain a polyvinylidene fluoride nanofiber composite membrane.

[0060] Comparative Example 4

[0061] The difference between Comparative Example 4 and Example 2 lies in step (6). Step (6) is changed to: polyvinylidene fluoride (Mw = 600,000) and dimethylformamide are mixed at a mass ratio of 0.35:9 and stirred at 40°C and 500 rpm until the solution is transparent to obtain an ultrafine polyvinylidene fluoride spinning solution. Then, electrospinning is performed at an ambient temperature of 25°C and a humidity of 30%. The spinning process parameters are: spinning flow rate 5 mm / min, positive voltage 30 kV, negative voltage 2 kV, and receiving distance 22 cm to obtain an ultrafine polyvinylidene fluoride fiber membrane. This membrane is then superimposed on the scaffold polyvinylidene fluoride fiber membrane to form two layers and sewn together to obtain a polyvinylidene fluoride nanofiber composite membrane. The remaining steps are the same as in Example 2.

[0062] Example of effect

[0063] Table 1 below shows the performance analysis results of the disinfection high-efficiency air filter paper used in Examples 1 to 3 and Comparative Examples 1 to 4 of the present invention.

[0064] Table 1

[0065]

[0066]

[0067] A comparison of the antibacterial rate data of the examples and comparative examples in Table 1 reveals that the present invention utilizes the reaction of N-(2,3-epoxypropyl)phthalamide with chitosan, and under the action of ethylene (chloromethyl)dimethoxysilane-modified titanium dioxide, converts it into quaternary ammonium groups, achieving basic antibacterial properties. Simultaneously, the combined action of chitosan and titanium dioxide enhances the antibacterial effect. Furthermore, the burst resistance and filtration performance experimental data of the examples and comparative examples show that utilizing a scaffolded polyvinylidene fluoride / fluorinated polyurethane fiber membrane composite ultrafine polyvinylidene fluoride fiber membrane, with the addition of… Tetrabutylammonium chloride increases the charge density of the polyvinylidene fluoride-fluorinated polyurethane polymer, achieving a burst-resistant composite membrane. It also gives the spun fiber membrane small pore size and uniform structure, stacking it into a fluffy, high-porosity composite membrane for low resistance. Meanwhile, the presence of fluorinated polyurethane enhances the interaction between the emulsion and the polyvinylidene fluoride nanofiber composite membrane, strengthening the burst-resistant properties of the filter paper. Furthermore, modified titanium dioxide can be fixed on the substrate surface, forming a rough surface structure rich in porous particles, further improving burst resistance.

[0068] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for preparing a high-efficiency disinfection air filter paper, characterized in that, The preparation steps include the following: (1) Mix nano-titanium dioxide and 15wt% dilute hydrochloric acid solution at a mass ratio of 1:60~1.3:65, sonicate at 25kHz for 30min, stir at 70~100rpm for 3~5h, add distilled water until the solution pH is 7, then add anhydrous ethanol at 85~100 times the mass of nano-titanium dioxide, filter, take the solid, wash with ethanol 3 times, vacuum dry at 50℃ for 2~3h, add 10~15 times the mass of nano-titanium dioxide in 80% ethanol aqueous solution, while stirring at 50~70rpm and adding 0.7~1 times the mass of nano-titanium dioxide in ethylene (chloromethyl)dimethoxysilane, sonicate at 40℃ and 25kHz for 40min, then heat to 70~100℃, react for 22~26h, cool to room temperature, filter, take the solid, wash with distilled water 3 times, vacuum dry at 50℃ for 2~3h to obtain modified titanium dioxide; (2) Mix chitosan and distilled water at a mass ratio of 6:8~7:10, heat to 80℃, stir at 70~100rpm for 30min, add N-(2,3-epoxypropyl)phthalamide at 2~4 times the mass of chitosan in three portions over 2h, react for 10h, pour in acetone at 30~35 times the mass of chitosan, stir at 70~100rpm for 1h, react at 0~4℃ for 12~15h, pour out the supernatant, dissolve the remaining gel-like product in methanol at 15~18 times the mass of chitosan, add acetone mixture at 25~29 times the mass of chitosan, the mass ratio of acetone to ethanol in the acetone mixture is 4:1, let stand for 2~3h, filter, take the solid, wash twice with ethanol at 50~65℃, dry at 70℃ for 4~6h to obtain modified chitosan; (3) Mix modified titanium dioxide, dichloromethane and modified chitosan in a mass ratio of 1:20:0.7~1:20:0.9 and react in a water bath at 35°C for 4~6h. Then heat to 60°C and distill under a vacuum of 1.4~3kPa for 2~3h. Let stand for 5~8h to obtain intermediate A. (4) After mixing acrylamide, N-hydroxymethylacrylamide and intermediate A in a mass ratio of 5:1.8:3.5~7:2.2:5, add 0.7 g / s to a composite emulsifier in a mass ratio of 1.7~2.3 times that of acrylamide, and add 3~4 times that of deionized water in a mass ratio of acrylamide. Stir at 100~200 rpm for 30 min to obtain a pre-emulsion. Mix deionized water, composite emulsifier and sodium bicarbonate buffer solution in a mass ratio of 7:2:0.1~10:4:0.2, heat in a water bath to 75°C, add 1 / 3 of the pre-emulsion and 1 / 2 of the ammonium persulfate initiator, heat to 85°C, add the remaining pre-emulsion and initiator at 3.5 h and 4 h of reaction respectively, continue heating for 2 h, pour off the supernatant to obtain an antibacterial emulsion. (5) Mix polyvinylidene fluoride, fluorinated polyurethane and dimethylformamide with a MW of 300,000 and stir at 60°C and 400 rpm until the solution is transparent to obtain a scaffold polyvinylidene fluoride / fluorinated polyurethane spinning solution. Then add tetrabutylammonium chloride and then perform electrospinning. The spinning process parameters are: spinning flow rate 10 mm / min, positive voltage 25 kV, negative voltage 2 kV, and receiving distance 18 cm to obtain a scaffold polyvinylidene fluoride fiber membrane. (6) Mix polyvinylidene fluoride (PVDF) and dimethylformamide (DMF) with a MW of 600,000 at a mass ratio of 0.2:8~0.5:10, and stir at 40℃ and 500 rpm until the solution is transparent to obtain an ultrafine PVDF spinning solution. Then, perform electrospinning with the following spinning process parameters: spinning flow rate 5 mm / min, positive voltage 30 kV, negative voltage 2 kV, and receiving distance 22 cm to obtain an ultrafine PVDF fiber membrane. Stack the membrane layer by layer with the scaffold PVDF fiber membrane to four layers and sew them together to obtain a PVDF nanofiber composite membrane. (7) Spray the antibacterial emulsion evenly on both sides of the polyvinylidene fluoride nanofiber composite membrane with a thickness of 0.3 mm. After standing at room temperature for 30-60 min, spray a second time with a thickness of 0.5 mm. Dry at 100-120℃ for 2 h to obtain disinfected high-efficiency air filter paper.

2. The method for preparing a high-efficiency disinfection air filter paper according to claim 1, characterized in that, The vacuum degree mentioned in step (1) is 0.2~1kPa.

3. The method for preparing a high-efficiency disinfection air filter paper according to claim 1, characterized in that, The preparation method of the composite emulsifier in step (4) is as follows: Sodium dodecylbenzenesulfonate, alkylphenol polyoxyethylene ether, and distilled water are mixed in a mass ratio of 4:1:13~6:1:

17. Acrylamide of 1.4~1.9 times the mass of sodium dodecylbenzenesulfonate is added dropwise to the solution at 0.3~0.5mL / s. The mixture is stirred at 70~100rpm for 30min to obtain the composite emulsifier.

4. The method for preparing a high-efficiency disinfection air filter paper according to claim 1, characterized in that, The mass ratio of ammonium persulfate initiator to acrylamide in step (4) is 0.7:1 to 0.9:

1.

5. The method for preparing a high-efficiency disinfection air filter paper according to claim 1, characterized in that, The mass ratio of polyvinylidene fluoride, fluorinated polyurethane, dimethylformamide, and tetrabutylammonium chloride in step (5) is 1:5:0.8:0.9~3:10:1.3:2.

5.

6. The method for preparing a high-efficiency disinfection air filter paper according to claim 1, characterized in that, The spinning environment described in steps (5) and (6) is a temperature of 25°C and a humidity of 30%.

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